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The ARK™ Zonisamide Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of zonisamide in human serum or plasma samples on automated clinical chemistry analyzers. Zonisamide concentrations can be used as an aid in management of patients treated with zonisamide.

The ARK™ Zonisamide Calibrator is intended for use in calibration of the ARK Zonisamide Assay.

The ARK™ Zonisamide Control is intended for use in quality control of the ARK Zonisamide Assav.

The ARK Zonisamide Assay is a homogeneous immunoassay based on competition between drug in the specimen and zonisamide labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for binding to the antibody reagent. As the latter binds antibody, enzyme activity decreases. In the presence of drug from the specimen, enzyme activity increases and is directly proportional to the drug concentration. Active enzyme converts the coenzyme nicotinamide adenine dinucleotide (NAD) to NADH that is measured spectrophotometrically as a rate of change in absorbance. Endogenous serum G6PDH does not interfere with the results because the coenyzme NAD functions only with the bacterial enzyme used in the assay.

The ARK Zonisamide Assay consists of reagents R1 anti-zonisamide polyclonal antibody with substrate and R2 zonisamide labeled with bacterial G6PDH enzyme. The ARK Zonisamide Calibrator consists of a six-level set to calibrate the assay, and the ARK Zonisamide Control consists of a three-level set used for quality control of the assay.

Here's a breakdown of the acceptance criteria and the study details for the ARK Zonisamide Assay, based on the provided 510(k) summary:

Acceptance Criteria and Device Performance

Study Details

1. Sample sizes used for the test set and the data provenance:

   • LOQ: 20 replicates for each sample. Data provenance not specified (likely laboratory-prepared samples).
   • Recovery: 20 replicates for each sample. Data provenance not specified (likely laboratory-prepared samples with added drug).
   • Linearity: Zonisamide concentrations ranged from 0.8 to 80.0 ug/mL, with dilutions made proportionally. Data provenance not specified (likely laboratory-prepared samples).
   • Method Comparison: 176 samples. Data provenance not specified.
   • Precision: 160 replicates per control level and human serum level (quadruplicate twice a day for 20 days). Data provenance not specified (likely laboratory-prepared controls and pooled human serum specimens).
   • Interfering Substances: Zonisamide levels of approximately 15 and 45 µg/mL, spiked with various interferents. Specific number of samples per interferent not specified, but each was "evaluated." Data provenance not specified (likely laboratory-prepared samples).
   • Metabolites: Zonisamide levels of 15 µg/mL and 45 µg/mL, spiked with NAZ (50.0, 10.0 µg/mL) and SMAP (50.0, 10.0 µg/mL). Data provenance not specified (likely laboratory-prepared samples).
   • Drug Interference: Zonisamide levels of approximately 15 and 45 µg/mL, spiked with various drug compounds. Specific number of samples per drug not specified, but each was "assayed." Data provenance not specified (likely laboratory-prepared samples).
   • Anticoagulants: Not explicitly stated, but "studies were conducted" on serum and plasma. Data provenance not specified.
   • Sample Stability: Not explicitly stated, but "serum specimens were shown to be stable" under various conditions. Data provenance not specified.
   • On-Board Stability: "Supporting data" cited, but specific sample sizes and provenance not detailed.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • No expert ground truth was described for the test set. The ground truth for analytical performance studies (LOQ, recovery, linearity, precision) is typically established by precisely preparing samples with known concentrations. For method comparison, the predicate device serves as the comparative "truth."

3. Adjudication method for the test set:

   • Not applicable, as this is an in vitro diagnostic assay and not an image-based or qualitative diagnostic device requiring expert adjudication.

4. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

   • Not applicable. This is an in vitro diagnostic assay, not an AI-assisted diagnostic tool for human readers.

5. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:

   • Yes, the entire submission describes the standalone performance of the ARK Zonisamide Assay. Its function is to quantitatively determine zonisamide concentrations in samples, which is an algorithm-only (analytical assay) performance.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

   • Analytical Ground Truth: For most studies (LOQ, recovery, linearity, interfering substances, drug interference, metabolites), the ground truth was established through gravimetrical or volumetric preparation of samples with known, spiked concentrations of zonisamide or interfering substances.
   • Comparative Ground Truth: For the method comparison study, the predicate device (QMS® Zonisamide Assay) served as the reference for comparison.

7. The sample size for the training set:

   • The document does not describe a "training set" in the context of machine learning or AI. This assay is a chemical immunoassay, not a learning algorithm. The studies described are analytical validation studies to characterize the performance of the chemical reaction and measurement system.

8. How the ground truth for the training set was established:

   • As there is no described training set, this question is not applicable.

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